This invention relates to rectangular screen printing frames and in particular to an improvement in screen printing frame corner connectors.
Existing rectangular screen printing frames are intended to support the screen mesh while maintaining an even strain on on the screen at all points when the screen is having ink forced through it. Uneven screen tension causes uneven printing of the desired image. Hence, a rigid and strong frame is required to obtain the best results, requiring strong and lightweight components.
Typical screens are made out of extruded aluminum hollow tubing side members with rectangular cross-sections. The side members are connected at the corners by welding the ends of the side members together or by fastening them to connectors. Welding the frames together is expensive and requires relatively thicker metal in the side members, thereby increasing the weight of the screen. A lower cost approach is to make the corner connectors such that the side members slide into them fixedly and are then glued or fastened.
A recurring problem with screen printing frames is that they need to be washed with water regularly between uses. While aluminum does not absorb water, a pinhole in a weld will allow water into the hollow frame interior. Washed screens are then air dried. Regardless of how well the screens are dried, there is usually residual water left in the frame members or connectors, and the water will drip onto the substrate, mixing with the printing ink. Existing inventions do not address this problem.
The prior art discloses brackets as in U.S. Pat. No. 2,545,277, tensioners as in U.S. Pat. Nos. 3,908,293 and 6,038,969, screw adjusters as in U.S. Pat. Nos. 5,076,162, 5,802,971 and 5,255,600, and internal connectors with mitred ends U.S. Pat. No. 4,452,138.
None of these devices have drain holes nor do the provide a four-sided connection between the side members. U.S. Pat. No. 4,452,138 teaches a mitred, 45-degree angle two-side connection that has less strength than the present invention.
This invention differs from the above-listed devices by virtue of its low-cost manufacture, its ease of assembly with frame side members, and its self-drying capability. Note that this invention is not to be used with wooden screen frames, which are mitred at the corners.
It is an object of this invention to provide a screen printing frame connector that is low-cost to manufacture.
It is an object of this invention to provide a screen printing frame connector that is strong and durable in use.
It is an object of this invention to provide a screen printing frame connector that facilitates the drying of the frame by means of strategically placed holes.
It is a further object of this invention to provide a screen printing connector that is four-sided instead of two-sided.
Further objects of this invention can be discerned by perusing the detailed description, drawings, specifications and claims of this application.